What are the factors affecting the workability of the Concrete ? Workability tests conducted on freshly prepared concrete

The concrete is the mixture of cement, fine aggregates (sand), coarse aggregates (stones) with suitable amount of the water. It is one of the most important property of the freshly prepared concrete in the specified grade. It is the property of the concrete which determines the amount of the useful internal work necessary to produce the full compaction. In this article you are able to learn about various important workability tests carried out on the freshly prepared concrete and factors affecting the workability of concrete. Depending upon the workability of the concrete strength value changes. The main reason of increase in the workability of the freshly prepared concrete is due to the effect of the excess of the water in the concrete mix. According to the Abrams law it was suggested that if the water content in the concrete mix increases workability of the concrete increases at the same time the strength of the concrete value is reduced. In the same process if the water content in the concrete mix decreases workability of the concrete decreases at the same time the strength of the concrete value is increases.

Some important tests conducted on workability of concrete

The following are the some of the important tests conducted on the freshly prepared concrete

1. Slump cone test
2. Compaction factor test
3. Vee bee consistometer test

Slump cone test

The slump test is a field test. This test is not suitable for the very low and very high workability condition. Slump cone test is carried out with the help of the slump cone equipment. Which is having top diameter of 10 centimeters, bottom diameter of 20 centimeters and height is 30 centimeters. There are three types of slumps are exists for any concrete which are related to the true slump, shear slump and collapsible slump.

Compaction factor test

The compaction factor test is determined with the help of compaction factor test equipment. It is the ratio of the weight of partial compacted concrete to the weight of fully compacted concrete.

Vee bee consistometer test

Vee bee consistometer test is generally used to determine the time taken for the settle down the concrete in the cylinder of vee bee consistometer set up.

Along with above specified three tests the flow table test and Kelly ball tests are used to determine the workability of the concrete mix.

Factors affecting the workability of the concrete

The following are the seven major factors considered in the workability of concrete which are

Water content

This is the first factor which affects the workability, if the water content in the concrete increases workability of the concrete increases at the same time strength of concrete decreases. At the same time if the water content in the concrete decreases workability of the concrete decreases at the same time strength of concrete increases.

Mix proportions

The mix proportions in the concrete will affects the workability of the concrete. If the ratio of aggregates to cement is high the value of the workability decreases which is results in high compressive strength values. At the same time the ratio of aggregates to cement is high the value of the workability increases which is results in less compressive strength values.

Size of the aggregates

This is the third factor which affects the workability of concrete. If the size of the aggregates increases the value of workability increases at the same time due to higher workability the strength value decreases. At the same time if the size of the aggregates decreases the value of workability decreases at the same time due to higher workability the strength value increases.

Shape of the aggregates

Shape of the aggregates influence the workability of the freshly prepared concrete. Basically aggregates has two types which are related to the angular and rounded one. For the aggregates of angular the workability is less and for the rounded aggregates the workability is higher. Due to this condition the higher values strength is observed in rough aggregates and If the size of the aggregates increases the value of workability increases at the same time due to lesser workability the strength value increases.

Grade of aggregates

Grade of the aggregates affects the workability of concrete. For the well graded aggregates the workability of the freshly prepared concrete increases and due to this reason the value of strength of the concrete is decreases for the specified grade.

Use of admixture

Admixture is one of the important ingredient which results in strength of the concrete mix. If we use admixture in the freshly prepared concrete the value of the workability of the concrete increases, due to this reason the value of strength of the concrete is decreases for the specified grade.

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Conclusions of various different factors considered in the workability of the freshly prepared concrete mix

Well now the above explained concepts are related to the various types factors affecting the workability of the concrete. Basically the seven factors steps which are related to the, water content, mix proportions, size of aggregates, shape of the aggregates, surface texture of aggregates, grading of the aggregates and finally use of admixture. Mainly the workability is measured with the help of slump cone test, compaction factor test and vee bee consistometer test along with these three tests the flow table test and Kelly ball tests are used to determine the workability. Depending upon the type of concrete the slump is consisting of three types related to the true slump, shear slump and collapsible slump.

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Note: The above concepts and information only helps for the civil engineering students to get brief idea regarding the topic. Do not consider it for the real time applications.

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